\begin{tikzpicture}
    \begin{scope}
        \tkzDefPoints{0/0/B, 2/0/C, 2/3/A}

        \tkzDrawPolygon(A,B,C)
        \tkzMarkRightAngle(A,C,B)
        \tkzLabelPoints[above](A)
        \tkzLabelPoints[below](B,C)
    \end{scope}

    \begin{scope}[xshift=3cm]
        \tkzDefPoints{0/0/B, 1.5/0/C, 2.5/2.8/A}

        \tkzDrawPolygon(A,B,C)
        \tkzLabelPoints[above](A)
        \tkzLabelPoints[below](B,C)
    \end{scope}

    \begin{scope}[xshift=6cm]
        \tkzDefPoints{0/0/B, 3.2/0/C, 2.5/2.3/A}

        \tkzDrawPolygon(A,B,C)
        \tkzLabelPoints[above](A)
        \tkzLabelPoints[below](B,C)
    \end{scope}
\end{tikzpicture}

